As a sheepy, I of course luff to wear T-shirts.....and now..it seems I like to microwave them too !

Look here,

[ Invalid Attachment ] My T Shirt In the M'Wave A Few Moments Ago**

I thought Microwaves only heated stuff that had water in it !..so how does my microwave heat up my dry T-shirt ?..Cook for 30 seconds on high and it was nice and warm !

Do the Microwaves do any harm to my T-shirt ? Have I part cooked my T-shirt ?

There's no label saying what it's made from but it is a kind of lavender colour (like as if that really matters !..DOH !)

So, whajafink ?

Hugs & Shmishes

mwah mwah mwah !

NeilExecutive officer In Charge Of Asking This Questionxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

**Polite note: This site does not condone the microwaving of lavender coloured T-shirts !..or any other colour for that matter...or any other type of clothing....or any non food stuffs ! (this include my wifes cooking)

Microwaves heat up anything that has molecules that are polar, ie, where the charge distribution is uneven on the molecule. Water is the most common, but many things are able to be heated in a microwave. Easiest that comes to mind in the winter is the overpriced bags of reject Chinese wheat that are sold as warmers, to be used instead of a hot water bottle. They are microwaved for a few minutes until they are hot. These contain no water, especially after being warmed up. You also find ceramic ware that heats up, while others are unaffected. Heating depends on the molecules getting energy added, either from contact with a hotter object, or via being moved by a high power RF energy field. Thus remember that microwaves heat not only water, but almost any thing that is placed inside them, it is just that most of the time the water is a major component of the goods added.

Just remember that they can cause things to catch on fire if heated too long. My sister needed a new microwave after she did this one day, as she would dry dishcloths in the microwave and one day the time was around a minute too much...............

As to the label saying do not microwave, I would point out that a "Reasonable Person" would have read the instruction manual for the microwave, where it says that it is to be used for food only.........

Microwaves heat up anything that has molecules that are polar, ie, where the charge distribution is uneven on the molecule. Water is the most common, but many things are able to be heated in a microwave. Easiest that comes to mind in the winter is the overpriced bags of reject Chinese wheat that are sold as warmers, to be used instead of a hot water bottle. They are microwaved for a few minutes until they are hot. These contain no water, especially after being warmed up. You also find ceramic ware that heats up, while others are unaffected. Heating depends on the molecules getting energy added, either from contact with a hotter object, or via being moved by a high power RF energy field. Thus remember that microwaves heat not only water, but almost any thing that is placed inside them, it is just that most of the time the water is a major component of the goods added.

Just remember that they can cause things to catch on fire if heated too long. My sister needed a new microwave after she did this one day, as she would dry dishcloths in the microwave and one day the time was around a minute too much...............

As to the label saying do not microwave, I would point out that a "Reasonable Person" would have read the instruction manual for the microwave, where it says that it is to be used for food only.........

This is a fantastic answer for which I am very grateful SeanB.

As soon as you mentioned the ceramics and the wheeat heating thingies ....the penny dropped. Your excellent information just hit it home !

yes.....yes...next time I will condcut an experiment to read the instructions.......

As I wrote on another thread a few days ago, a microwave oven pumps 700watts (or whatever it's rated for) of microwave energy into the enclosure - it has to go somewhere. If there's nothing in the oven that is a more effective absorber, it'll still put heat into poorer absorbers in there.

Energy which doesn't get absorbed in the main cavity will inevitably be dissipated in the magnetron (which generates the microwaves in the first place), and if the oven is operated for too long with too little absorbing material in there then the magnetron is likely to overheat (potentially destructively).

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"It has been said that the primary function of schools is to impart enough facts to make children stop asking questions. Some, with whom the schools do not succeed, become scientists." - Schmidt-Nielsen "Memoirs of a curious scientist"

If you put a low loss material such as polyethylene or PTFE in there it wouldn't absorb much of the Radio Frequency energy very much and might damage the magnetron. I am not sure what happens to a magnetron with no load. It might actually produce less RF output but still use the same or even more DC power and it will overheat.

lyner

As I wrote on another thread a few days ago, a microwave oven pumps 700watts (or whatever it's rated for) of microwave energy into the enclosure - it has to go somewhere. If there's nothing in the oven that is a more effective absorber, it'll still put heat into poorer absorbers in there.

Energy which doesn't get absorbed in the main cavity will inevitably be dissipated in the magnetron (which generates the microwaves in the first place), and if the oven is operated for too long with too little absorbing material in there then the magnetron is likely to overheat (potentially destructively).

Actually, it may not actually deliver its rated power unless it is working into an appropriate load. If a transmitter is not 'matched' to its load, it may overvolt (high standing wave ratio, it's called 'in the trade') or you can get excessive currents flowing in the cavities. I think it may not be as much of a problem with modern devices as popular opinion suggests. If it really were such a potential risk, there could always be protective cut-outs installed to save excessive damage.How many catastrophic failures have we actually heard of? I've not heard of one.